1. Field
The present invention relates generally to switching voltage regulators. More specifically, the present invention relates to embodiments for operating a switching voltage regulator at or near a current limit with enhanced efficiency, and without impacting regulation.
2. Background
An electronic device, such as a mobile telephone, may include a voltage regulator that receives an input voltage from a power supply and generates an output voltage for a load. An integrated circuit may include a voltage regulator for providing a stable voltage reference for on-chip components such as a digital component, an analog component, and/or a radio-frequency (RF) component.
A voltage regulator may comprise a switching voltage regulator, which rapidly switches a power transistor between triode (i.e., completely on) and cutoff (i.e., completely off) with a variable duty cycle. A resulting rectangular waveform is low pass filtered in order to produce a nearly constant output voltage proportional to the average value of the duty cycle. One advantage of a switching voltage regulator compared to a linear voltage regulator is greater efficiency because the switching transistor dissipates little power as heat in either a saturated state or a cutoff state.
As understood by a person having ordinary skill in the art, limiting an output current of a switching voltage regulator is important to protect from output short-circuit conditions, which can cause almost immediate permanent damage to an associated device. Conventional devices and methods for reducing output current may cause a severe and immediate reduction in the output current when an over-current condition is detected, even transiently, thus causing an output voltage to fall out of regulation.
A need exists for an enhanced switching voltage regulator. More specifically, a need exists for embodiments related to operating a switching voltage regulator at or near a current limit with enhanced efficiency and regulation.